it comes from Meteogroup. They do have and provide their own data.
Weather stations
In conjunction with a number of partners, we operate our own private weather measurement network with approximately 1600 stations around the world. Our network of weather stations across Germany and Switzerland is the highest density of private weather stations in Europe. These stations provide the essential basis for our reliable and high-precision forecasts.
https://www.meteogroup.com/about-meteogroup


